diff --git a/apps/ai-pipeline-studio-app/app.py b/apps/ai-pipeline-studio-app/app.py
index 579e968..9944fa0 100644
--- a/apps/ai-pipeline-studio-app/app.py
+++ b/apps/ai-pipeline-studio-app/app.py
@@ -4453,10 +4453,24 @@ def _fmt_project_dir(dir_name: str) -> str:
         )
         openai_key = (openai_key_input or "").strip()
         st.session_state["OPENAI_API_KEY"] = openai_key
+        default_openai_base_url = st.session_state.get("OPENAI_BASE_URL")
+        if default_openai_base_url is None:
+            default_openai_base_url = os.environ.get("OPENAI_BASE_URL", "")
+        openai_base_url_input = st.text_input(
+            "OpenAI base URL (optional)",
+            value=default_openai_base_url,
+            key="openai_base_url_input",
+            help="Override OpenAI base URL, e.g. http://localhost:8000/v1",
+        )
+        openai_base_url = (openai_base_url_input or "").strip()
+        st.session_state["OPENAI_BASE_URL"] = openai_base_url
 
         if openai_key:
             try:
-                _ = OpenAI(api_key=openai_key).models.list()
+                client_kwargs = {"api_key": openai_key}
+                if openai_base_url:
+                    client_kwargs["base_url"] = openai_base_url
+                _ = OpenAI(**client_kwargs).models.list()
                 key_status = "ok"
                 st.success("API Key is valid!")
             except Exception as e:
@@ -4886,6 +4900,9 @@ def _fmt_dataset(did: str) -> str:
 # LLM credentials are only required when running chat (Pipeline Studio + previews should still work).
 llm_provider_selected = st.session_state.get("llm_provider") or "OpenAI"
 resolved_api_key = (st.session_state.get("OPENAI_API_KEY") or "").strip() or None
+resolved_openai_base_url = (
+    (st.session_state.get("OPENAI_BASE_URL") or "").strip() or None
+)
 resolved_ollama_model = (st.session_state.get("ollama_model") or "").strip() or None
 
 
@@ -4893,6 +4910,7 @@ def build_team(
     llm_provider: str,
     model_name: str,
     openai_api_key: str | None,
+    openai_base_url: str | None,
     ollama_base_url: str | None,
     use_memory: bool,
     sql_url: str,
@@ -4935,6 +4953,15 @@ def _openai_requires_responses(model: str | None) -> bool:
             "model": model_name,
             "api_key": openai_api_key,
         }
+        if openai_base_url:
+            try:
+                sig = inspect.signature(ChatOpenAI)
+                if "base_url" in sig.parameters:
+                    llm_kwargs["base_url"] = openai_base_url
+                elif "openai_api_base" in sig.parameters:
+                    llm_kwargs["openai_api_base"] = openai_base_url
+            except Exception:
+                llm_kwargs["base_url"] = openai_base_url
         if _openai_requires_responses(model_name):
             llm_kwargs["use_responses_api"] = True
             llm_kwargs["output_version"] = "responses/v1"
@@ -5952,6 +5979,7 @@ def _apply_chat_dataset_selection() -> None:
             llm_provider_selected,
             model_choice,
             resolved_api_key if llm_provider_selected == "OpenAI" else None,
+            resolved_openai_base_url if llm_provider_selected == "OpenAI" else None,
             st.session_state.get("ollama_base_url"),
             add_memory,
             st.session_state.get("sql_url", DEFAULT_SQL_URL),
diff --git a/apps/exploratory-copilot-app/app.py b/apps/exploratory-copilot-app/app.py
index cf96e67..8fe5181 100644
--- a/apps/exploratory-copilot-app/app.py
+++ b/apps/exploratory-copilot-app/app.py
@@ -8,6 +8,8 @@
 # !pip install git+https://github.com/business-science/ai-data-science-team.git --upgrade
 
 from openai import OpenAI
+import inspect
+import os
 import streamlit as st
 import streamlit.components.v1 as components
 import pandas as pd
@@ -186,9 +188,21 @@ def render_report_iframe(
     type="password",
     help="Your OpenAI API key is required for the app to function.",
 )
+default_openai_base_url = st.session_state.get("OPENAI_BASE_URL")
+if default_openai_base_url is None:
+    default_openai_base_url = os.environ.get("OPENAI_BASE_URL", "")
+st.session_state["OPENAI_BASE_URL"] = st.sidebar.text_input(
+    "Base URL (optional)",
+    value=default_openai_base_url,
+    help="Override OpenAI base URL, e.g. http://localhost:8000/v1",
+)
 
+openai_base_url = (st.session_state.get("OPENAI_BASE_URL") or "").strip() or None
 if st.session_state["OPENAI_API_KEY"]:
-    client = OpenAI(api_key=st.session_state["OPENAI_API_KEY"])
+    client_kwargs = {"api_key": st.session_state["OPENAI_API_KEY"]}
+    if openai_base_url:
+        client_kwargs["base_url"] = openai_base_url
+    client = OpenAI(**client_kwargs)
     try:
         models = client.models.list()
         st.success("API Key is valid!")
@@ -199,7 +213,25 @@ def render_report_iframe(
     st.stop()
 
 model_option = st.sidebar.selectbox("Choose OpenAI model", MODEL_LIST, index=0)
-OPENAI_LLM = ChatOpenAI(model=model_option, api_key=st.session_state["OPENAI_API_KEY"])
+def _chat_openai_kwargs(model_name, api_key, base_url):
+    kwargs = {"model": model_name, "api_key": api_key}
+    if base_url:
+        try:
+            sig = inspect.signature(ChatOpenAI)
+            if "base_url" in sig.parameters:
+                kwargs["base_url"] = base_url
+            elif "openai_api_base" in sig.parameters:
+                kwargs["openai_api_base"] = base_url
+        except Exception:
+            kwargs["base_url"] = base_url
+    return kwargs
+
+
+OPENAI_LLM = ChatOpenAI(
+    **_chat_openai_kwargs(
+        model_option, st.session_state["OPENAI_API_KEY"], openai_base_url
+    )
+)
 llm = OPENAI_LLM
 
 # =============================================================================
diff --git a/apps/pandas-data-analyst-app/app.py b/apps/pandas-data-analyst-app/app.py
index cef9a77..c6152eb 100644
--- a/apps/pandas-data-analyst-app/app.py
+++ b/apps/pandas-data-analyst-app/app.py
@@ -9,6 +9,8 @@
 
 from openai import OpenAI
 
+import inspect
+import os
 import streamlit as st
 import pandas as pd
 import plotly.io as pio
@@ -67,11 +69,23 @@
     type="password",
     help="Your OpenAI API key is required for the app to function.",
 )
+default_openai_base_url = st.session_state.get("OPENAI_BASE_URL")
+if default_openai_base_url is None:
+    default_openai_base_url = os.environ.get("OPENAI_BASE_URL", "")
+st.session_state["OPENAI_BASE_URL"] = st.sidebar.text_input(
+    "Base URL (optional)",
+    value=default_openai_base_url,
+    help="Override OpenAI base URL, e.g. http://localhost:8000/v1",
+)
 
 # Test OpenAI API Key
+openai_base_url = (st.session_state.get("OPENAI_BASE_URL") or "").strip() or None
 if st.session_state["OPENAI_API_KEY"]:
     # Set the API key for OpenAI
-    client = OpenAI(api_key=st.session_state["OPENAI_API_KEY"])
+    client_kwargs = {"api_key": st.session_state["OPENAI_API_KEY"]}
+    if openai_base_url:
+        client_kwargs["base_url"] = openai_base_url
+    client = OpenAI(**client_kwargs)
 
     # Test the API key (optional)
     try:
@@ -89,7 +103,25 @@
 
 model_option = st.sidebar.selectbox("Choose OpenAI model", MODEL_LIST, index=0)
 
-llm = ChatOpenAI(model=model_option, api_key=st.session_state["OPENAI_API_KEY"])
+def _chat_openai_kwargs(model_name, api_key, base_url):
+    kwargs = {"model": model_name, "api_key": api_key}
+    if base_url:
+        try:
+            sig = inspect.signature(ChatOpenAI)
+            if "base_url" in sig.parameters:
+                kwargs["base_url"] = base_url
+            elif "openai_api_base" in sig.parameters:
+                kwargs["openai_api_base"] = base_url
+        except Exception:
+            kwargs["base_url"] = base_url
+    return kwargs
+
+
+llm = ChatOpenAI(
+    **_chat_openai_kwargs(
+        model_option, st.session_state["OPENAI_API_KEY"], openai_base_url
+    )
+)
 
 
 # ---------------------------
diff --git a/apps/sql-database-agent-app/app.py b/apps/sql-database-agent-app/app.py
index 8bd2d69..f08be13 100644
--- a/apps/sql-database-agent-app/app.py
+++ b/apps/sql-database-agent-app/app.py
@@ -9,6 +9,8 @@
 
 from openai import OpenAI
 
+import inspect
+import os
 import streamlit as st
 import sqlalchemy as sql
 import pandas as pd
@@ -69,11 +71,23 @@
 st.sidebar.header("Enter your OpenAI API Key")
 
 st.session_state["OPENAI_API_KEY"] = st.sidebar.text_input("API Key", type="password", help="Your OpenAI API key is required for the app to function.")
+default_openai_base_url = st.session_state.get("OPENAI_BASE_URL")
+if default_openai_base_url is None:
+    default_openai_base_url = os.environ.get("OPENAI_BASE_URL", "")
+st.session_state["OPENAI_BASE_URL"] = st.sidebar.text_input(
+    "Base URL (optional)",
+    value=default_openai_base_url,
+    help="Override OpenAI base URL, e.g. http://localhost:8000/v1",
+)
 
 # Test OpenAI API Key
+openai_base_url = (st.session_state.get("OPENAI_BASE_URL") or "").strip() or None
 if st.session_state["OPENAI_API_KEY"]:
     # Set the API key for OpenAI
-    client = OpenAI(api_key=st.session_state["OPENAI_API_KEY"])
+    client_kwargs = {"api_key": st.session_state["OPENAI_API_KEY"]}
+    if openai_base_url:
+        client_kwargs["base_url"] = openai_base_url
+    client = OpenAI(**client_kwargs)
     
     # Test the API key (optional)
     try:
@@ -95,9 +109,24 @@
     index=0
 )
 
+def _chat_openai_kwargs(model_name, api_key, base_url):
+    kwargs = {"model": model_name, "api_key": api_key}
+    if base_url:
+        try:
+            sig = inspect.signature(ChatOpenAI)
+            if "base_url" in sig.parameters:
+                kwargs["base_url"] = base_url
+            elif "openai_api_base" in sig.parameters:
+                kwargs["openai_api_base"] = base_url
+        except Exception:
+            kwargs["base_url"] = base_url
+    return kwargs
+
+
 OPENAI_LLM = ChatOpenAI(
-    model = model_option,
-    api_key=st.session_state["OPENAI_API_KEY"]
+    **_chat_openai_kwargs(
+        model_option, st.session_state["OPENAI_API_KEY"], openai_base_url
+    )
 )
 
 llm = OPENAI_LLM